1. Field of the Invention
This invention relates to a fault display and interface unit for a vehicle electronic control system, such as an adaptive braking system.
2. Description of Prior Art
Vehicle electronic control systems, such as adaptive braking systems, normally work quite well and are very reliable. However, because of the environmental and physical stresses to which components of these systems are subjected due to their being mounted in the adverse environment on the exterior of the vehicle, such systems occasionally malfunction. Many of these malfunctions are rather simple to correct. For example, a common malfunction is a shorted or open sensor or modulator fault, which may be caused by a broken wire, a connector being vibrated loose, etc. Such malfunctions are relatively simple for even a relatively untrained mechanic to correct. Furthermore, some malfunctions are intermittent. Since the warning device is activated only during such a malfunction the warning device is not activated until the malfunction occurs again. Accordingly, there is no easily accessible record of such a malfunction, so that even if the vehicle was serviced in the interim the defect probably would not have been either noted or corrected.
U.S. Pat. No. 4,837,552 discloses a unit where a series of light emitting diodes (LEDs) are provided on the housing within which the electronic control unit component of the system is mounted. The disclosure of U.S. Pat. No. 4,837,552 is incorporated herein by reference. In the unit disclosed in the patent each of the light emitting diodes is activated in response to a predetermined discrete fault in the system. For example, one of the light emitting diodes may be activated in response to a fault in one of the wheel speed sensors, and another of the light emitting diodes may be activated in response to a malfunction in one of the modulators. Accordingly, a relatively unskilled mechanic is able to examine the wires, connectors, etc. associated with the corresponding wheel speed sensor or modulator. If a broken wire is found or a loose connector is discovered, the mechanic can quickly repair the system, perhaps in the field, thereby saving valuable time that would ordinarily be required to send the vehicle to a maintenance location to perform more sophisticated diagnostic tasks. Of course, if the mechanic is unsuccessful in locating such a simple failure, or if the light emitting diode corresponding to a fault in, for example, the system logic controller is activated, the driver knows immediately that the vehicle must be taken to a maintenance location where a mechanic skilled in repairing electronic systems is available.
The faults sensed by the system and indicated on the light emitting diodes are stored in a non-volatile memory when the system is powered down. Once a malfunction occurs, the malfunction is stored in memory, and the corresponding indicator is activated upon system powerup at a later time. Accordingly, if a transient or intermittent failure does occur, the mechanic repairing the system will immediately know that such a fault has occurred at some time during the operation of the vehicle. However, the diagnostics LEDs have proven to be difficult to observe when installed in an obscure location on the vehicle framerail or reservoir.